Hi, I've been working with Sencha for a few weeks now and I really enjoy working with the framework. However, I'm having trouble accessing a nested model within my data store. I'm using a json data source and manually populating it because the initial stage of my project is a demo and doesn't yet have a database set up. My store is called newJSONStore and it's model property is 'CourseItem'. The CourseItem model contains several properties (id, title, module, unit, page) and a nested model called 'ContentItem'. I can get all the properties of the CourseItem model, but for some reason when I debug this, I can't get the 'ContentItem' model to show up as a property in the debugger. I tried the same exercise with the kitchensink demo's nested data loading example and I was able to see the nested model showing up as a property of the data object in the debugger. So my question is, what's preventing me from seeing my nested model? I think I created everything according to the documentation, so I need help understanding what I need to do differently. Is the problem with my json or with my sencha code?
My code is below:

here's an example of one of my json code objects, there are several of them, in the content.json file, and all look like this:

Here's my Sencha code. You can see that I have a callback to handleJsonLoad2 and that's where I set a breakpoint in the debugger to view the objects returned from the load. I can see id, title, module, unit, page, but I should also see contentItems and I can't see it.